The pH, or hydrogen ion concentration, [H+], of natural environments varies from about 0.5 in the most acidic soils to about 10.5 in the most alkaline lakes. The range of pH over which an organism grows is defined by the minimum pH, below which the organism cannot grow or reproduce; the maximum pH, above which the organism cannot grow or reproduce; and the optimum pH, at which the organism grows best. For most organisms there is an orderly increase in growth rate and reproduction rate between the minimum and the optimum pH and a corresponding orderly decrease in growth rate and reproduction rate between the optimum and the maximum pH, reflecting the general effect of changing [H+] on the rates of enzymatic reaction.
The pH of interstitial and intracellular fluids in mammals is one of the physiologic barriers that contribute to innate immunity. For example, gastric acidity provides an innate physiologic barrier to infection because very few ingested microorganisms can survive the low pH of the stomach. Hair follicles secrete sebum that contains lactic acid and fatty acids both of which inhibit the growth of some pathogenic bacteria and fungi.
In contrast to the acidity of gastric acid and sebum, blood and lymph are both slightly alkaline with the optimal pH of blood maintained between a pH 7.3 to 7.4 and the pH of lymph at about 7.5. An alteration in the normal pH of any of these fluids may make an individual more susceptible to infection and disease by creating a more hospitable environment for microorganisms to grow.
The pH of the human body is maintained through the actions of buffers, respiration, and renal function. In dealing with the normal acid load from diet and metabolism, buffers such as proteins, phosphate and H2CO3:HCO3— act to control the pH level. Respiration maintains a constant carbonic acid level at 1.2 meq/l or PaCO2 of 40 mmHG through either excretion or retention of CO2 by the lungs. Respiration can also rapidly compensate for changes in pH by altering the level of PaCO2 through the alteration of alveolar ventilation. The renal system manipulates the volume and composition of extracellular fluid to help maintain the pH of plasma. However, while the renal system can correct states of excess, it cannot correct states of deficiency such as through loss of Na+, K+ or HCO3−. Unlike respiratory regulation, regulation of pH through renal function can take several days.
A natural byproduct of the normal metabolism of oxygen is reactive oxygen species (ROS). ROS are generally very small molecules such as free radicals, oxygen ions and peroxides that are highly reactive due to the presence of unpaired valence shell electrons. While these molecules play an important roll in cell signaling, during times of environmental stress ROS levels can increase dramatically resulting in significant damage to cell structures. ROS have been implicated in aging, cancer, cardiovascular disease as well as other kinds of cellular damage to the body.
Cells normally protect themselves from reactive oxygen species through free radical scavengers and chain reaction terminators including enzymes such as superoxide dismutase (SOD), catalase, and the glutathione peroxidase system as well as other antioxidants; however, antioxidant supply is non-catalytic in nature and one antioxidant molecule can only react with a single free radical. Therefore, there is a constant need to replenish antioxidant resources, whether endogenously or through supplementation.
Failure or overloading of any one of these regulatory mechanisms, whether through stress, pharmacological treatments, diet, infection, lactic acidosis, and other diseases and conditions, including but not limited to, cancer, cardiovascular disease, metabolic diseases and disorders, diabetes, cellulitis and pancreatic impairment. There is therefore a need for compositions that can compensate for the failure of regulatory mechanisms to regulate physiological pH and prevent acidosis as well as reduce levels of reactive oxygen species.